This is a program in medical mycology. Each of the research projects contained in the program is concerned with an important area of medical mycology and is directed by an expert in that area. Although the program is divided into separate projects, they are interrelated and strengthened by this interaction. In effect, this is a coordinated approach to the objective of improving the outcome of systemic fungal infections. The projects in the program involve the following: 1. The molecular biology of growth and phase transition of the dimorphic pathogenic fungus Histoplasma capsulatum. 2. Development of new sensitive and specific diagnostic methods which will allow earlier diagnosis of systemic fungal infections. 3. Host fungal interactions which involve the role of humoral and cell mediated immune responses to pathogenic fungi. 4. Development of new forms of chemotherapy and more efficient use of the older agents. 5. A coordinated effort using the participants in the program to teach a modern approach to medical mycology.